Many short-circuits arise during closing operations, since a suitable tripping device of a circuit breaker, for example, does not function until the short circuit is already flowing. In the same way, many circuits remain connected, although no current is being drawn. Even in the case of overvoltage and undervoltage, the circuits usually remain closed for the most part. For some of the problems described, partial solutions, exist such as undervoltage tripping devices for contactors and circuit breakers, as well as short-circuit tripping devices in circuit breakers.